Replace unnecessary format macro with `to_string()`

Rust pattern

Checks for the use of format!("string literal with no argument") and format!("{}", foo) where foo is a string.

Replaces a string literal with no argument

BEFORE
let hi = format!("hello");
AFTER
let hi = "hello".to_string();

Replaces with one string literal argument

BEFORE
let greeting = "hello";
let hi = format!("{}", greeting);
AFTER
let greeting = "hello";
let hi = greeting.to_string();

Does not replace necessary formats

RUST
let hi = format!("hello {}", "world");
let another = format!("{:?}", strawberry);